Universal thermoplastic sheet forming apparatus

ABSTRACT

One or more heating stations, a dual action pressure-vacuum thermo-forming press, and a die-cutting press are located in line on a single machine. Thermoplastic sheet is fed from a supply roll under the heating stations and through the forming and cutting presses and then passed over a separating mechanism. Precise indexing of the thermo-formed parts from the forming press through the cutting press is provided by a pin chain carriage assembly. Pins on the chain engage the plastic sheet and hold it fixed with respect to the chain. The entire chain mechanism is mounted on a carriage which is reciprocated. When the carriage moves forward, parts are indexed from under the thermo-forming press to the first of one of more intermediate stations between it and the cutting press. When the carriage is reciprocated backwards, the chain is driven through a one-way clutch assembly such that the chain remains stationary with respect to the presses. Thus, on a subsequent reciprocation, the thermo-formed parts are precisely indexed in the cutting press. The cutting press is mounted on rails and may be positioned towards or away from the forming press to eliminate waste even when small parts are formed using single molds. The thermo-forming press is provided with separate top and bottom platen-driving cylinders for universal adjustment of initial and final positions and strokes. The drive cylinders are mounted in a parallel battery below the top and bottom platens. Fixed parallel cold bars transverse to the carriage mechanism permit clamping of the sheet during thermo-forming. The cutting press is driven by a single cylinder through a toggle mechanism, providing a long down stroke on the top platen to engage the cutting die about the plastic parts in a self centering action prior to raising the lower platen against the parts to provide the cutting action.

United States Paten [191 Butzko 1 UNIVERSAL THERMOPLASTIC SHEET FORMINGAPPARATUS 211 App]. No.2 139,632

[52] US. Cl 425/289, 425/388, 425/397,

425/398, 425/400, 425/412, 425/D1G. 220 [51] Int. Cl. 82% 17/04 [58]Field of Search 425/398, 292, 306,

[56] References Cited UNITED STATES PATENTS 3,105,270 10/1963 Fibish425/145 3,346,923 10/1967 Brown et al. 425/162 3,359,600 12/1967 OBrienet al. 425/157 3,504,074 3/1970 Snow 425/163 X 3,561,057 2/1971Butzko...... 425/214 3,513,505 5/1970 Brown et al. 425/306 X 3,518,3346/1970 Carrigan et al. 425/397 X 3,632,250 1/1972 Snow 425/307 X3,357,054 12/1967 Hartman, Jr 425/161 3,605,215 9/1971 Young et a1.425/161 X Primary Examiner-Robert L. Spicer, Jr. AttorneyMattern, Ware &Davis [57] ABSTRACT One or more heating stations, a dual actionpressurevacuum thermo-forming press, and a die-cutting press are locatedin line on a single machine. Thermoplastic 1 90 1 l6 1 r 20 l 100 224Jan. 115, 1974 sheet is fed from a supply roll under the heatingstations and through the forming and cutting presses and then passedover a separating mechanism. Precise indexing of the thermo-formed partsfrom the forming press through the cutting press is provided by a pinchain carriage assembly. Pins on the chain engage the plastic sheet andhold it fixed with respect to the chain. The entire chain mechanism ismounted on a carriage which is reciprocated. When the carriage movesforward, parts are indexed from under the thermo-forming press to thefirst of one of more intermediate stations between it and the cuttingpress. When the carriage is reciprocated backwards, the chain is driventhrough a one-way clutch assembly such that the chain remains stationarywith respect to the presses. Thus, on a subsequent reciprocation, thethermo-formed parts are precisely indexed in the cutting press. Thecutting press is mounted on rails and may be positioned towards or awayfrom the forming press to eliminate waste even when small parts areformed using single molds.

The thermo-forming press is provided with separate top and bottomplaten-driving cylinders for universal adjustment of initial and finalpositions and strokes. The drive cylinders are mounted in a parallelbattery below the top and bottom platens. Fixed parallel cold barstransverse to the carriage mechanism permit clamping of the sheet duringthermo-forming. The cutting press is driven by a single cylinder througha toggle mechanism, providing a long down stroke on the top platen toengage the cutting die about the plastic parts in a self centeringaction prior to raising the lower platen against the parts to providethe cutting action.

22 Claims, 8 Drawing Figures PATENIEUJAH 1 5mm 3 7 85 sum 2 or 3 FIG. 3

:1 UNIVERSAL THERMOPLASTIC SHEET FORMING APPARATUS SUMMARY OF THEINVENTION This invention relates to universal thermo-plasticsheet-forming apparatus and more particularly to such apparatus capableof forming and cutting at two separate stations parts of any size lessthan the maximum dimensions of the cutting press. Many thermoplasticsheet-forming machines have been designed according to the prior art.Machines such as illustrated in my U.S. Pat. No. 3,561,057, issued Feb.9, l97l, provide for precise cutting of thermo-formed parts, since thecutting dies are located coaxially with the forming molds, and thecutting action actually takes place in the forming press. However, sincethe cuting dies are located right next to the forming molds, there arevarious restrictions on the shapes of the parts which may be made onsuch a machine. I

On the other hand, other machines according to the prior art haveseparate forming and cutting presses and the formed plastic parts mustbe indexed from the forming press to the cutting press. These machines,although able to form and cut a larger variety of plastic parts, haveserious indexing problems. That is, the 'parts cannot be repetitivelyindexed under the cutting dies to close tolerances. This leads to partshaving larger nonfunctional flanges than necessary, which vary indimension, depending upon the speed that the machine is operated. Mostmachines according to the prior art move the plastic sheet with a chainmechanism bearing pins which pass through the edge of the plastic sheet.These chain mechanisms when driven relatively fast to provide quickindexing and high volume production tend to overrun due to the inertiaof the chain. This overtravel is quite unpredictable, varying accordingto the amount of heating the sheet has undergone in the machine, whichmakes it relatively easier to move along than when it is cold, and otherfactors which will be apparent to those skilled in the art.-

Thus, when highly accurate cutting is desired in the prior art, theparts are formed on one machine and then sent to a separate cuttingmachine. This transfer step greatly increases the labor costs of suchparts.

Prior art machines having separate cutting and indexing stations employpresses which are large and unwieldy. The presses are fixed to a largeheavy frame structure. When parts smaller than the press size are to beformed using a less expensive single mold, the distance between thepresses may not be an integral number times the width of the parts. Thisresults in large spaces between the formed parts on the plastic sheet, aconsequent waste of material.

Prior art thermo-forming machines also provide restrictions on the userin the form and height of the molds they may use, since the machineshave fixed strokes for the forming platens and fixed initial and finalpositions which restrict the way in which the molds may be machined. Theforming presses of prior art machines are usually provided with chilledperipheral sheet-engaging means for holding the sheet during thethermo-forming process, and these means often make it difficult toconstruct molds for use on such machines.

Other problems of prior art thermo-forming machines having die-cuttingpresses independent of the thermo-forming presses l have found arecaused by the restriction that the top and bottom platens of thediecutting .press meet at the'plane of the sheet simultaneously. l havefound that as a consequene the parts, although somewhat flexible, areunable to adjust themselves to the cutting dies, but that, if the upperfemale cutting die is allowed to engage the male portions of a partfirst, the part may be guided therein to closer tolerance registrationprior to bringing'up the lower platen to close the cutting dies and cutthe part.

OBJECTS or THE INVENTION It is therefore a primary object of theinvention to improve the art of thermo-forming plastic sheet.

Another object of the invention is to provide appara tus for forming andcutting thermoplastic articles from 'thermo-plastic sheet to closetolerances without restriction on the shape of the parts or thecloseness of the cut to the formed portion of the part.

Still another object of the invention is to provide apparatus of theabove character capable of forming parts of any size smaller than themaximum platen size provided with no wastage of thermoplastic sheetmaterial and without the use of multiple molds.

Yet another object of the invention is to provide highly accurateplastic sheet indexing mechanism for apparatus of the above character.

Still another object of the invention is to provide apparatus of theabove character comprising a vacuumpressure press capable of universaladjustment of initial and final positions of top and bottom platens.

Yet another object of the invention is to provide compact mechanism foroperating a thermo-forming press of the above character.

A further object of the invention is to provide sheet- -holdingapparatus for a forming press of the above character which does notrestrict the nature of the forming dies employed.

Another object of the invention is to provide a diecutting press forapparatus of the above character, providing a self-aligning feature.

Still another object of the invention is to provide a cutting press ofthe above character, providing very high cutting force.

Yet another object of the invention is to provide apparatus of the abovecharacter which is compact, relatively light in weight, convenient touse, and relatively inexpensive.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

I The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following description taken in connectionwith the accompanying drawings, in which:

THE DRAWINGS cording to the invention;

FIG. 2 is a fragmentary side view of the apparatus of FIG. 1 showingportions of the apparatus cut away in FIG. 1;

FIG. 3 is a fragmentary cross-sectional along the lines 3-3 of FIG. 1',

FIG. 4 is a fragmentary cross-sectional along the lines 4-4 of FIG. 3;

FIG. 5 is a fragmentary cross-sectional along the lines 55 of FIG. 1;

FIG. 6 is a fragmentary cross-sectional along the lines 66 of FIG. 1;

FIG. 7 is a fragmentary cross-sectional along the lines 77 of FIG. I;and

FIG. 8 is a schematic diagram illustrating the operation of the cuttingpress of the apparatus of FIG. 1.

The same reference characters refer to the same elements throughout theseveral views of the drawings.

Apparatus according to the invention generally comprises conventionalmeans for holding a roll of thermoplastic sheet; a novel reciprocatingcarriage on which are mounted parallel chains carrying pins for engagingthe thermo-plastic sheets in a conventional manner; a gear mounted tothe drive sprockets of 'the sheetengaging chains through a one-wayclutch such that the chains remain fixed with respect to the carriageupon forward motion of the carriage and are driven exactly equally andoppositely to the carriage upon backward motion of the carriage, thuskeeping the sheet stationary during backward motion; heating means forheating the plastic sheeting; a fixed pressure-vacuum thermoformingpress; a movable die-cutting press which can be moved toward and awayfrom the forming press; conventional means for separating thethermoplastic parts from the sheets together with takeup means for theseparated strip the separating means being intermittently driven byreciprocation of the carriage mechanism; and controls for operating theindexing means and presses in synchronism.

The pressure-vacuum thermo-forming press generally comprises a topplaten and a bottom platen. The bottom platen is driven by a cylinderlocated below it and the top platen is driven by a pair of cylinders onopposite sides of the bottom cylinder below the bottom platen anddriving the top platen by means of rods passing up through the bottomplaten on which the top platen is mounted. The die-cutting presscomprises a top and bottom platen, which are driven by a togglemechanism similar to that disclosed in any aboveidentified US. Pat. No.3,561,057. The toggle mechanism is arranged such that a novel cuttingaction is employed wherein the upper die comes down around the part,providing a self centering action, and thereupon the lower platen raisesup to complete the cutting action. Non-reciprocating cold bars areprovided at the cutting press which may be engaged by separate upperknives to hold the plastic sheet during forming. The cold bars which areparallel and transverse to the chains may be adjusted laterally fordifferent size parts.

view taken view taken view taken view taken view taken SPECIFICDESCRIPTION More specifically referring to FIG. I, a thermoformingmachine according to the invention, generally indicated at 20, comprisesthe usual rigid frame structure 22, to which are mounted a pair of rigidrails 24 and 26 (see also FIG. 5). A thermo-forming pressurevacuumpress, generally indicated at 28, is mounted on rails 24 and 26 by meansof screws 30 and 32, as seen in FIG. 1, and another pair of screws 34,only one of which may be seen in FIG. 5.

38 and 40 and 42 and 44 (FIG. 6). The die cutting press 1 36 may bepositioned towards and away from the thermo-forming press 28 by means ofadjustable positioning members 46, only one of which is shown.

Now referring to FIG. 2, a conventional supply reel 48 of thermoplasticsheet 50 is mounted on the frame 22 in a conventional manner by meansnot shown, and the sheet 50 is fed over a guide roller 52 at the leftend of the machine shown in FIG. 1. After the parts have been formed,the sheet 50 with the parts 54 formed thereon is supplied to aseparating mechanism generally indicated at 56 in FIG. 2, which ismounted to the frame 22 by means which are not shown in detail. At theseparating mechanism 56, the parts 54 are separated from the remainingsheet 50 in a conventional manner.

Again referring to FIG. I, the sheet 50 enters the machine from the leftand is supplied to a carriage mechanism generally indicated at 58. Thecarriage 58 comprises a frame structure 60 supported by means of sleevebearings 66, 68 and 70 on an elongated guide rail rod 72 and supportedon the other side on a square rail 74, as shown in FIG. 5. The carriage58 is reciprocated upon rails 72 and 74 by means of a fluid cylinderactuator 76 mounted on rail 24. Roller wheels 69 and 71 assist inguiding the carriage 58 on rail 72.

The carriage 58 further comprises a pair of pin chain belts 78 and 80(FIG. 5), which engage and guide the sheet under chanelled guides 79 and81 in the conventional way. The chains 78 and 80 are mounted on endsprockets 82 at the left end of the carriage, as seen in FIG. I, and endsprockets 84 at the right end of the carriage, as seen in FIG. 1. Thesprockets 82 are mounted on a common shaft 86 (FIG. 3). The sprockets 82are keyed to the shaft 86 so that they are driven together. The shaft 86is connected to a one way clutch 88, which is driven by a gear 90, gear90 being driven by rack 92. Rack 92 is mounted at one end to the frame22. To insure contact between the rack 92 and gear 90, roller 93 ismounted to the top of carriage frame 60 as shown in FIG. 3.

Gear 90 and sprockets 82 have the same effective diameter. The one wayclutch 88 is connected such that the shaft 86 is rotated only uponbackward motion of the carriage 58 from the right to the left, as seenin FIG. 1. Thus, on forward motion of the carriage 58, the plastic sheet50 is indexed the distance traveled by the carriage 58. This distance Smay be adjusted by adjusting the stops 94 and 96, seen in FIG. I.

When the carriage 58 returns to the left, rotation of the shaft 86 onwhich the sprockets 82 are mounted causes the two chains to remainstationary with respect to the entire apparatus 20, readying thecarriage mechanism 58 for the next indexing reciprocation.

Referring to FIGS. 1 and 5, the thermo-forming pressure-vacuum press,generally indicated at 28, comprises a bottom platen 98 and a top platen100 on which are mounted a mold 102 and a mold assist 104. The bottomplaten 98 is pressed upwardly by a fluid actuator I06 mounted rigidlybetween an upper fixed plate 108 and a lower fixed plate 110 which withtie plates I12 and 114 form a rigid frame for the thermoforming press28. Upper platen 100 is adjustably mounted on four reciprocating shafts116 movable in sleeve bearings 118 in bottom platen 98, sleeve bearings120 in rigid top plate 108, and sleeve bearings 122 in rigid bottomplate 110. A lower reciprocating plate 124 is mounted to shafts 116 andis moved by means of the fluid actuators 126 and 128, which are mountedto the rigid bottom plate 110. Stops 130 and 132 may be mounted toplates 108 and 110 to limit the open positions of the top and bottomplatens 98 and 100. The closed positions of the platens 98 and 100 areat the plane of the sheet 50. Normally the top platen is actuated firstdown against the sheet, then the bottom platen is pushed up to close themold. The top platen is provided with slightly greater force than thebottom platen and thus defines the closed position.

The cutting press 36, as seen in FIGS. 1, 6 and 7, comprises a topplaten 136 and a bottom platen 138 on which are mounted the cuttingdies, generally indicated at 140. In the illustrated embodiment of theinvention, the cutting dies comprise a female guiding die 142 havingcutting knives 144 mounted on top platen 136, and a lower cutting plate146 mounted on bottom platen 138. As in the thermo-forming press 28, thetop platen 136 is adjustably mounted on four shafts 148. The shafts 148are reciprocated through sleeve bearings 150 in the bottom platen andsleeve bearings 152 mounted to the rigid frame 154 of the cutting press36.

The cutting press platens 136 and 138 are operated by a toggle mechanismmounted between the bottom platen 138 and a shaft 156 adjustably mountedto the lower end of the rods 148 at tie plates 158 and 160. The togglemechanism is connected to the bottom platen 138 at shaft 162 mountedthereon by trunnions 164. The upper toggle arm comprises a pair of arms166, and the lower toggle arm also comprises a pair of arms 168, whichcan rock on the shafts 162 and 156 respectively. The toggle arms 166 and168 are tied together on a common shaft 170, to which is also mounted anactuator head 172.

Actuator head 172 is connected to the shaft 174 of a fluid actuator 176,best seen in FIG. 1. As shown diagramatically in FIG. 8, the toggle isopened by pushing the actuator head 172 to the left, as seen in FIGS. 1and 8, and closed by pulling the actuator head 172 to the right to theposition shown in FIG. 1. As explained below, the actuator 176 rocks onshaft 77 mounted to frame 154.

As best seen in FIG. 8, starting in the full open position, the centralshaft of the toggle 170 is all the way to the left; the bottom platen138 is at its lowermost position; and the upper platen 136 is at itshighest position, as indicated by solid lines. In closing the press,shaft 170 is pulled to the right to the position shown in cross section.Because of the weight of the structure, during this movement the bottomplaten 138 does not move. However, shaft 156 moves to the position shownin cross-section. Shaft,.156 continues to move until a bottom-most tieplate 179 mounted to shaft 148 (see FIG. 6) engages stop 178 mounted onthe frame structure 154, thus defining the lowermost position of theupper platen 136, the lowermost position attained by shaft 156 beingshown in dotted lines. Thereafter, as the actuator 174 pulls the shaft170 to the right, as seen in FIG. 8, the lower platen 138 is raised onlyone half inch to the position shown by the dotted line. In this way, theupper female die 142 may be moved five inches to engage the male portionof the part 54 and self-center the part under the cutting knives 144prior' to the small movement of the lower cutting plate 146 to completethe die cut. Those skilled in the art will understand that the knives144 could also be located on the lower plate 146, if desired.

Another feature of the machine is the convenient positioning of coldbars 180 on either side of the molds 102 and 104, on which are mountedholding knives 182, which cooperate with the lower edges 184 of the moldassist 104 to clamp the sheet 50 during the molding operation. Cold bars180 have conduits therein for cooling fluid and are mounted in a channel186 in the carriage 58. Thus, they may be conveniently spaced closertogether or farther apart, depending on the size of the part beingformed. This eliminates the need for separate closed clamping members asin the prior art machines, which greatly restrict the form of the moldsused and require separate holding members for different sizes and shapesof parts.

Summarizing the operation of the machine, the sheet 50 is fed in themachine from the left (see FIG. 1) to the carriage mechanism generallyindicated at 58, where it is clamped between the pins of the chains 78and and the upper grooved plates 79 and 81 (as best seen in FIG. 5). Thematerial is indexed to the right by movement of the carriage mechanism58 under control of the actuator 76. This indexing is of an amount Sequal to the width of the part or parts being made in one operation ofthe thermo-forming press 28. The thermo-forming press 28 providesuniversal adjustment of stroke and very convenient means 182 forclamping and holding the sheet 50 during the thermo-forming process.

The parts 54 are then indexed through one or more blank stations duringwhich they cool until they come under the cutting press 36, which may beadjusted before the parts are formed by means of adjustment bar 46, sothat the distance between the thermo-forming molds 102 and 104 and thecutting dies 142 are exactly a multiple of the parts width S. Aspreviously stated, during the forward indexing of the carriage adistance S equal to the part width S, the chain 78 moves with thecarriage 58. However, on the return stroke, the oneway clutch 88 engagesand drives the chain under the action of the stationary rack 92, causingthe chain to remain stationary keeping the parts 54 in position withrespect to the machine 20. This reverse motion prefera bly takes placeduring the thermo-forming and cutting cycle when the presses 28 and 36are closed, which aids in holding the sheet 50, and provides a longperiod of time for the reverse stroke of the carriage so that the chaindoes not need to be driven fast and inertial problems may be avoided.

The cutting action provided by the cutting press 36, wherein the upperdie registers with the part before the lower die moves a short distanceto complete the cut, provides for compensation for minor variations inthe parts as they are molded and indexed. The stripper mechanism 56shown in FIG. 2 is actuated incrementally. Since rack 200 is mounted tothe carriage 58, it drives a chain mechanism 202 through a slip clutch(not shown). Pawl gear mechanism 203 prevents back motion. The sheet 50is thus indexed between rollers generally indicated at 204 the indexingdistance S each time the carriage 58 is reciprocated.

material and be driven only on the return stroke, and that during thisperiod they are climbing onto cold sheet 50, thus providing reproduciblefriction conditions and leading toward the high indexing accuraciesproduced by apparatus according to this invention.

The machine 20, as seen in FIG. 1, may be provided with one or morepairs of heaters 220, 222 and 224 and 226 for heating the thermoplasticsheet 50 prior to molding.

Those skilled in the art will understand that the machine may beoperated through any conventional cutting and forming cycle byconventional controls, which form no part of the present invention. Themolds 102 and 104 of FIG. 1 may be supplied with vacuum or pressure asdesired. The actuators may be actuated by hydraulic or pneumatic means,whichever is more convenient for the forces and conditions under whichthe machine is to be operated. Furthermore, the chains 78 and 80 arepreferably mounted on the carriage 58 such that the space between themmay be varied to handle various widths of plastic sheet 50. Othernecessary and desirable features of a commercial machine will be obviousto those skilled in the art and are not shown or discussed here indetail.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain 'changes may be made in the above construction withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

Having described my invention, what 1 claim as new and desire to secureby letters patent is:

l. A universal thermoforming machine comprising:

A. a forming press;

B. a cutting press;

C. indexing mechanism for feeding sheet material therebetweencomprising:

a. a reciprocating carriage,

b. holding means movably mounted on said carriage for continuouslyengaging and holding at least one edge of a sheet,

c. means for driving said holding means, said sheet and said carriagetogether when said carriage moves in one direction, and,

d. means for causing said holding means and said sheet to remainstationary when said carriage moves in the opposite direction.

2. A universal thermoforming machine as defined in claim 1, and:

D. means for adjusting the spacing between said forming and said cuttingpresses.

3. A universal thermoforming machine comprising;

A. a forming station;

B. a cutting station;

C. a carriage for indexing parts from said forming station to saidcutting station;

D. an endless loop conveyor mounted on said carriage;

E. means for reciprocating said carriage; and,

F. means for causing said endless loop conveyor to 8 remain stationarywith respect to said carriage when said carriage moves in one directionand to cause a portion of said endless loop conveyor to remainstationary with respect to said stations when said carriage moves in theopposite direction.

4. A universal thermoforming machine as defined in claim 3 wherein saidlast named means comprises:

a. a pulley mounted on said carriage for driving said conveyor,

b. a rack mounted in a fixed position with respect to said stations,

c. a pinion for engaging said rack mounted on said carriage having thesame effective diameter as said pulley, and

d. a one-way clutch mounted between said pinion and said pulley.

5. A universal thermoforming machine as defined in claim 3, and

G. means for adjusting the spacing between said forming and said cuttingpresses. 6. A universal thermoforming machine comprising: A. a moldingpress; and, B. a cutting press comprising:

a. a shaped die for engaging and centering a preformed part to be cut;

b. a mating die, said dies when pressed together cutting a part locatedbetween them;

c. means for first moving said shaped die into centering engagement witha similarly shaped part to be cut and for then pressing said mating dieagainst said shaped die to cut the part;

C. indexing mechanism for feeding sheet material therebetweencomprising;

a. a reciprocating carriage,

b. holding means movably mounted on said carriage for continuouslyengaging and holding at least one edge of a sheet,

c. means for driving said holding means, said sheet and said carriagetogether when said carriage moves in one direction, and,

d. means for causing said holding means and said sheet to remainstationary when said carriage moves in the opposite direction.

7. A universal thermoforming machine as defined in claim 6, and:

D. means for adjusting the spacing between said molding and said cuttingpresses. 8. A universal thermoforming machine as defined in claim 6,wherein said molding press comprises:

a. a plurality of. parallel shafts,

b. a top platen mounted to said shafts,

c. a bottom platen journaled to said shafts,

d. a rigid structure in which said parallel shafts are journaled,

e. a first fluid cylinder mounted to said rigid structure and to saidbottom platen for exerting a force therebetween,

f. a movable bottom plate mounted to said shafts,

and,

g. a second fluid cylinder mounted to said rigid structure and to saidmovable bottom plate for exerting a force therebetween.

9. A universal thermoforming machine as defined in claim 8, wherein saidmolding press further comprises:

h. a pair of parallel, transversely adjustable, cooled knives mountedjust below said holding means and,

i. a mating pair of knives mounted to one of said platens for holdingmaterial being formed in the molding press.

10. A universal thermoforming machine as defined in claim 6, and:

C. a carriage for indexing parts from said molding press to said cuttingpress;

D. an endless loop conveyor mounted on said carriage;

E. means for reciprocating said carriage; and,

F. means for causing said endless loop conveyor to remain stationarywith respect to said carriage when said carriage moves in one directionand to cause a portion of said endless loop conveyor to remainstationary with respect to said stations when said carriage moves in theopposite direction.

11. A universal thermoforming machine as defined in claim 10, whereinsaid last named means comprises:

a. a pulley mounted on said carriage for driving said conveyor,

b. a rack mounted in a fixed position with respect to said stations,

c. a pinion for engaging said rack mounted on said carriage having thesame effective diameter as said pulley, and

d. a one way clutch mounted between said pinion and said pulley.

12. A universal thermoforming machine as defined in claim 10, and

G. means for adjusting the spacing between said forming and said cuttingpresses.

13. A universal thermoforming machine as defined in claim 10, whereinsaid moving means of said cutting press comprises a toggle.

14. A universal thermoforming machine as defined in claim 13, whereinsaid moving means of said cutting means moves said shaped die through adistance substantially at least ten times greater than it moves saidat-il s i 15. A universal thermoforming machine as defined in claim 14,wherein said moving means of said cutting means moves said mating die adistance substantially equalto one-half inch.

116. A universal thermoforming machine as defined in claim 10, whereinsaid cutting press further comprises:

d. a plurality of parallel shafts, e. a top platen mounted to saidshafts on which said shaped die is mounted, f. a bottom platen journaledon said shafts on which said mating die is mounted, g. a movable bottomplate mounted to said shafts,

and, h. a rigid structure in which said parallel shafts are journaled,and wherein said moving means comprises:

l. a stop for limiting the downward motion of said movable bottom plate;

2. a toggle comprising a knee shaft mounted between said bottom platenand said movable bottom plate; and,

3. a fluid cylinder acting on said knee shaft to straighten said toggle,said knee shaft being free to move in an arc whereby as said toggle isstraightened said upper platen is first caused to move down with nomotion of said bottom platen until said movable bottom plate engagessaid stop and the said bottom platen is then caused to move up a smallerdistance than said upper platen is moved.

17. A cutting press for a universal thermoforming machine comprising:

A. a shaped die for engaging and centering a preformed part to be cut;

B. a mating die, said dies when pressed together cutting a part locatedbetween them;

C. means for first moving said shaped die into centering engagement witha similarly shaped part to be cut and for then pressing said mating dieagainst said shaped die to cut the part,

D. a plurality of parallel shafts;

E. a top platen mounted to said shafts on which said shaped die ismounted;

F. a bottom platen joumaled on said shafts on which said mating die ismounted;

G. a movable bottom plate mounted to said shafts;

and,

H. a rigid structure in which said parallel shafts are journaled,

and wherein said moving means comprises:

a. a stop for limiting the downward motion of said movable bottom plate;

b. a toggle comprising a knee shaft mounted between said bottom platenand said movable bottom plate; and,

c. a fluid cylinder acting on said knee shaft to straighten said toggle,said knee shaft being free to move in an arc whereby as said toggle isstraightened said upper platen is first caused to move down with nomotion of said bottom platen until said movable bottom plate engagessaid stop and the said bottom platen is then caused to move up a smallerdistance than said upper platen is moved.

18. A cutting press as defined in claim 17, wherein said moving meansmoves said shaped die through a distance substantially at least tentimes greater than it moves said mating die.

19. A cutting press as defined in claim 18., wherein said moving meansmoves said mating die a distance substantially equal to one-half inch.

20. A universal thermoforming machine as defined in claim 1 and:

e. a reciprocating force producing member for driving said carriage,and,

f. at least one adjustable stop for adjusting the stroke of said member.

21. A universal thermoforming machine as defined in claim 20 and:

D. means for adjusting the spacing between said forming and said cuttingpresses.

22. A universal thermoforming machine as defined in claim 3 wherein saidendless loop conveyor comprises a chain and said pulley is a sprocketpulley about which said chain is engaged.

1. A universal thermoforming machine comprising: A. a forming press; B.a cutting press; C. indexing mechanism for feeding sheet materialtherebetween comprising: a. a reciprocating carriage, b. holding meansmovably mounted on said carriage for continuously engaging and holdingat least one edge of a sheet, c. means for driving said holding means,said sheet and said carriage together when said carriage moves in onedirection, and, d. means for causing said holding means and said sheetto remain stationary when said carriage moves in the opposite direction.2. A universal thermoforming machine as defined in claim 1, and: D.means for adjusting the spacing between said forming and said cuttingpresses.
 2. a toggle comprising a knee shaft mounted between said bottomplaten and said movable bottom plate; and,
 3. a fluid cylinder acting onsaid knee shaft to straighten said toggle, said knee shaft being free tomove in an arc whereby as said toggle is straightened said upper platenis first caused to move down with no motion of said bottom platen untilsaid movable bottom plate engages said stop and the said bottom platenis then caused to move up a smaller distance than said upper platen ismoved.
 3. A universal thermoforming machine comprising; A. a formingstation; B. a cutting station; C. a carriage for indexing parts fromsaid forming station to said cutting station; D. an endless loopconveyor mounted on said carriage; E. means for reciprocating saidcarriage; and, F. means for causing said endless loop conveyor to remainstationary with respect to said carriage when said carriage moves in onedirection and to cause a portion of said endless loop conveyor to remainstationary with respect to said stations when said carriage moves in theopposite direction.
 4. A universal thermoforming machine as defined inclaim 3 wherein said last named means comprises: a. a pulley mounted onsaid carriage for driving said conveyor, b. a rack mounted in a fixedposition with respect to said stations, c. a pinion for engaging saidrack mounted on said carriage having the same effective diameter as saidpulley, and d. a one-way clutch mounted between said pinion and saidpulley.
 5. A universal thermoforming machine as defined in claim 3, andG. means for adjusting the spacing between said forming and said cuttingpresses.
 6. A universal thermoforming machine comprising: A. a moldingpress; and, B. a cutting press comprising: a. a shaped die for engagingand centering a preformed part to be cut; b. a mating die, said dieswhen pressed together cutting a part located between them; c. means forfirst moving said shaped die into centering engagement with a similarlyshaped part to be cut and for then pressing said mating die against saidshaped die to cut the part; C. indexing mechanism for feeding sheetmaterial therebetween comprising; a. a reciprocating carriage, b.holding means movably mounted on said carriage for continuously engagingand holding at least one edge of a sheet, c. means for driving saidholding means, said sheet and said carriage together when said carriagemoves in one direction, and, d. means for causing said holding means andsaid sheet to remain stationary when said carriage moves in the oppositedirection.
 7. A universal thermoforming machine as defined in claim 6,and: D. means for adjusting the spacing between said molding and saidcutting presses.
 8. A uniVersal thermoforming machine as defined inclaim 6, wherein said molding press comprises: a. a plurality ofparallel shafts, b. a top platen mounted to said shafts, c. a bottomplaten journaled to said shafts, d. a rigid structure in which saidparallel shafts are journaled, e. a first fluid cylinder mounted to saidrigid structure and to said bottom platen for exerting a forcetherebetween, f. a movable bottom plate mounted to said shafts, and, g.a second fluid cylinder mounted to said rigid structure and to saidmovable bottom plate for exerting a force therebetween.
 9. A universalthermoforming machine as defined in claim 8, wherein said molding pressfurther comprises: h. a pair of parallel, transversely adjustable,cooled knives mounted just below said holding means and, i. a matingpair of knives mounted to one of said platens for holding material beingformed in the molding press.
 10. A universal thermoforming machine asdefined in claim 6, and: C. a carriage for indexing parts from saidmolding press to said cutting press; D. an endless loop conveyor mountedon said carriage; E. means for reciprocating said carriage; and, F.means for causing said endless loop conveyor to remain stationary withrespect to said carriage when said carriage moves in one direction andto cause a portion of said endless loop conveyor to remain stationarywith respect to said stations when said carriage moves in the oppositedirection.
 11. A universal thermoforming machine as defined in claim 10,wherein said last named means comprises: a. a pulley mounted on saidcarriage for driving said conveyor, b. a rack mounted in a fixedposition with respect to said stations, c. a pinion for engaging saidrack mounted on said carriage having the same effective diameter as saidpulley, and d. a one way clutch mounted between said pinion and saidpulley.
 12. A universal thermoforming machine as defined in claim 10,and G. means for adjusting the spacing between said forming and saidcutting presses.
 13. A universal thermoforming machine as defined inclaim 10, wherein said moving means of said cutting press comprises atoggle.
 14. A universal thermoforming machine as defined in claim 13,wherein said moving means of said cutting means moves said shaped diethrough a distance substantially at least ten times greater than itmoves said mating die.
 15. A universal thermoforming machine as definedin claim 14, wherein said moving means of said cutting means moves saidmating die a distance substantially equal to one-half inch.
 16. Auniversal thermoforming machine as defined in claim 10, wherein saidcutting press further comprises: d. a plurality of parallel shafts, e. atop platen mounted to said shafts on which said shaped die is mounted,f. a bottom platen journaled on said shafts on which said mating die ismounted, g. a movable bottom plate mounted to said shafts, and, h. arigid structure in which said parallel shafts are journaled, and whereinsaid moving means comprises:
 17. A cutting press for a universalthermoforming machine comprising: A. a shaped die for engaging andcentering a preformed part to be cut; B. a mating die, said dies whenpressed together cutting a part located between them; C. means for fiRstmoving said shaped die into centering engagement with a similarly shapedpart to be cut and for then pressing said mating die against said shapeddie to cut the part, D. a plurality of parallel shafts; E. a top platenmounted to said shafts on which said shaped die is mounted; F. a bottomplaten journaled on said shafts on which said mating die is mounted; G.a movable bottom plate mounted to said shafts; and, H. a rigid structurein which said parallel shafts are journaled, and wherein said movingmeans comprises: a. a stop for limiting the downward motion of saidmovable bottom plate; b. a toggle comprising a knee shaft mountedbetween said bottom platen and said movable bottom plate; and, c. afluid cylinder acting on said knee shaft to straighten said toggle, saidknee shaft being free to move in an arc whereby as said toggle isstraightened said upper platen is first caused to move down with nomotion of said bottom platen until said movable bottom plate engagessaid stop and the said bottom platen is then caused to move up a smallerdistance than said upper platen is moved.
 18. A cutting press as definedin claim 17, wherein said moving means moves said shaped die through adistance substantially at least ten times greater than it moves saidmating die.
 19. A cutting press as defined in claim 18, wherein saidmoving means moves said mating die a distance substantially equal toone-half inch.
 20. A universal thermoforming machine as defined in claim1 and: e. a reciprocating force producing member for driving saidcarriage, and, f. at least one adjustable stop for adjusting the strokeof said member.
 21. A universal thermoforming machine as defined inclaim 20 and: D. means for adjusting the spacing between said formingand said cutting presses.
 22. A universal thermoforming machine asdefined in claim 3 wherein said endless loop conveyor comprises a chainand said pulley is a sprocket pulley about which said chain is engaged.